Extent of PFAS Soil Contamination
PFAS contamination in soil is associated primarily with AFFF use at military and airport sites, fluorochemical manufacturing facility operations and waste disposal, and biosolids land application. Surface soil contamination from AFFF at firefighting training areas can reach concentrations of thousands of micrograms per kilogram. These contaminated soils act as ongoing sources of PFAS leaching into groundwater, making soil remediation a key component of comprehensive PFAS site cleanup.
Excavation and Thermal Treatment
Soil excavation followed by off-site disposal or treatment is the most straightforward soil remediation approach for PFAS-contaminated sites, but is prohibitively expensive for large contamination areas and creates transportation and disposal challenges for the excavated material. High-temperature thermal treatment of excavated soil — using rotary kilns or electric arc furnaces at temperatures exceeding 900°C — destroys PFAS in soil but requires significant energy input and appropriate air pollution control to prevent PFAS emissions during treatment.
In-Situ Approaches
In-situ soil treatment avoids excavation by treating contamination in place. Soil washing using cosolvents, surfactants, or cyclodextrin solutions has shown laboratory-scale PFAS extraction from soil, with the resulting PFAS-concentrated wash solution requiring further treatment or disposal. In-situ chemical treatment approaches using reductants such as zero-valent iron or photocatalytic agents are being investigated for in-place PFAS degradation. The challenge is delivering treatment reagents uniformly through heterogeneous soil matrices.
Phytoremediation Research
Some plant species have demonstrated PFAS uptake from contaminated soil and groundwater in laboratory and greenhouse studies, raising interest in phytoremediation as a low-cost in-situ PFAS removal approach. However, PFAS accumulated in plant biomass must ultimately be harvested and disposed of — the problem is concentrated rather than destroyed unless plant material is subsequently incinerated. Field-scale demonstration of cost-effective PFAS phytoremediation remains an active research area without established commercial implementation at this time.